With the above-described valve timing controller, conventionally, the driving rotary member and the driven rotary member are formed of a single material such as an aluminum-based material, e.g. an aluminum alloy or an iron-based material, e.g. an iron-based sintered material, etc. (see e.g. Patent Document 1). Further, for the purpose of precision control of a spacing between the driving-side rotary member and the driven-side rotary member which are moved in sliding contact with each other, it is generally implemented to form the driving-side rotary member and the driven-side rotary member of a common material.